Browsing by Author "Pogson, RE"

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    Raman, FTIR and XRD study of Icelandic tephra minerals: implications for mars
    (John Wiley & Sons, Inc., 2015-04-27) Bathgate, E; Maynard-Casely, HE; Caprarelli, G; Xiao, L; Stuart, B; Smith, KT; Pogson, RE
    Essential to the success of proposed planetary Raman spectroscopy missions will be the preparation of comprehensive libraries of spectra and a greater understanding of the current limitations of Raman spectroscopy. Seven samples of Icelandic tephra were analysed using X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared (FTIR) as an analogue for Martian rocks. The results from these three spectroscopic techniques were compared with the success of mineral identification of each method differing. Some minerals such as ilmenite and flouroapatite were identified using XRD and not found in the Raman spectra. Olivine, hematite and anatase were detected by Raman spectroscopy but were not observed in the XRD patterns. The FTIR results gave essential information on the presence of H2O in the samples. The impact of fluorescence on Raman spectra of some minerals is still a major concern as this is the most likely reason for some of the diagnostic mineral peaks not showing in the Raman spectra. © 2015, John Wiley & Sons, Ltd.
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    Sulfate and phosphate speleothems at Jenolan Caves, New South Wales, Australia
    (Slovenian Academy of Sciences and Arts and ZRC SAZU Karst Research Institute, 2011-09-01) Pogson, RE; Osborne, RAL; Colchester, DM; Cendón, DI
    Sulfate and phosphate deposits at Jenolan Caves occur in a variety of forms and compositions including crusts, ‘flowers’ and fibrous masses of gypsum (selenite), and clusters of boss-like speleothems (potatoes) of ardealite (calcium sulphate, phosphate hydrate) with associated gypsum. This boss-like morphology of ardealite does not appear to have been previously described in the literature and this is the first report of ardealite in New South Wales. Gypsum var. selenite occurs in close association with pyrite-bearing palaeokarst, while the ardealite gypsum association appears to relate to deposits of mineralised bat guano. Isotope studies confirm that the two gypsum suites have separate sources of sulfur, one from the weathering of pyrite (-1.4 to +4.9 δ34S) for gypsum (selenite) and the other from alteration of bat guano (+11.4 to +12.9 δ34S) for the ardealite and gypsum crusts. © 2011 The Authors